CHICAGO – Significant strides have been made in reducingListeria monocytogenes(Lm) in the United States and other countries, thanks to aggressive food and equipment testing and zero tolerance for the bacteria, according to an expert panel at the 2010 Institute of Food Technologists Annual Meeting & Food Expo.

In 2003, the U.S. undertook a concerted effort to reduce Lm after two years of listeriosis outbreaks associated with ready-to-eat meat and poultry products, said Daniel Engeljohn, PhD, deputy assistant administrator, Office of Policy and Program Development, and acting assistant administrator, Office of Data Integration and Food Protection, at the U.S. Department of Agriculture’s Food Safety and Inspection Service.

Stepped-up prevention efforts have led to several changes, including a risk-based verification testing program that uses a formula to determine a product’s risk and therefore the frequency of sampling, Mr. Engeljohn said. In the past, establishments were tested at random, without regard for the likelihood of contamination. In addition, testing was expanded to 10,000 products annually and also includes environmental and food contact surface samples.

Mr. Engeljohn added the change has been significant. In 1990, 4.61% of R.T.E. products tested at random were positive for Lm. By 2009, that number declined to .38%.

Ewen C. D. Todd, a professor at Michigan State University and former head of the school’s National Food Safety and Toxicology Center, pointed to progress from the international community as well, stemming from a May 2009 meeting of experts. Participants in that workshop supported the Codex Alimentarius microbiological criteria forListeria monocytogenes in R.T.E. foods. A key component of that was to establish a zero tolerance for Lm in R.T.E. products where the bacteria could grow.